Effects of Hydrogen Blending Ratio and Fuel Axial Staged Ratio on Methane–Hydrogen Fuel Mixture Combustion Characteristics and NO$_x$ Emission of Double‐Swirl Axial Staged Burner

Staged combustion is a promising technology that offers a valuable pathway to achieve low NO$_x$ emission in CH$_4$–H$_2$ mixed combustion. This study explores the combustion characteristics and NO$_x$ emissions of a double-swirl axial staged burner operating at constant thermal power. The investigation focuses on the synergistic effects of varying fuel axial staged ratios (0.3, 0.5, 0.7) and hydrogen blending ratios (0%–50%) through Fluent numerical simulations. The results indicate that the fuel staged ratio and hydrogen blending ratio are crucial factors influencing the flow field configuration within the combustion chamber, with increased hydrogen blending enhancing fluid kinetic energy and strengthening recirculation zones. It also enhances the combustion temperature and improves the uniformity of temperature. In addition, the hydrogen addition leads to higher temperature and temperature uniformity inside the combustion chamber and the high-temperature zone extends and expands toward the inlet and outlet. Importantly, the appropriate axial staged fuel ratios (0.5) suppress the NO$_x$ generation, with a concentration of less than 150 mg m$^{−3}$ at hydrogen blending ratios ranging from 0% to 30%. ... mehrThis research contributes both a theoretical foundation and a technical pathway for the application of axial staged structures in CH$_4$–H$_2$ mixed combustion technology.